By the looks of it, you are almost there. Apart from the two identical lexical variables problem hardburn mentioned, all you need is getting the remote file: 
my $remote_file="remote_file";
my $openstring="/usr/bin/rexec $host -l $user cat $remote_file |";
# note the cat command, and the pipe at the end
open FILE, $remote_file or die "Blerch: $!\n";
$md5=Digest::MD5->new();
while (<FILE>) {
  $md5->add($_);
}
close FILE;
print $md5->b64digest;
warn "Code is untested.";

[download]
Of course this presumes your .rhosts or hosts.equiv files are set up correctly.

Update: Fixed typo in code (replaced [ by { )

CU
Robartes-

In reply to Re: md5 by robartes
in thread md5 digest of remote file by qball

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